Method of processing viscous hydrocarbon oils



Nov. 21, 1933. J. c. BLACK 1,935,693

METHOD OF PROCESSING vxscous HYDROCARBON oILs Filed March 21, 1930 QINVENTOR I a, JO/M/ c. snack ATfORNEY Patented Nov. 21, 1933 UNITEDSTATES PATENT OFFICE METHOD OF PROCESSING VISCOUS HYDROCABBON OILS Thisinvention relates to a method of processing hydrocarbon oils such ascrude petroleum oils, petroleum oil residuums, fuel oil and .the like,for the production of high boiling distillates and a marketable residuumsuitable for fuel oil and other like purposes.

By well-known methods, high boiling distillates such as gas oil andlubricating oil stocks are obtained by distillation of crude petroleumoil, or petroleum oil residuums in which a residuum may be obtainedwhich is too viscous for a marketable fuel oil without the addition of arelatively large amount of a solvent petroleum I oil distillate or othersolvents, to obtain a sumciently fluid mixture to meet the viscosityrequired for the various grades of fuel oil.

The petroleum oil distillates usually employed to reduce the viscosityof viscous petroleum oil residuums are light gas oil stocks which may ormay not contain lamp oil or other distillates which are sufficientlyfluid and of the least value for the production of refined marketableproducts. It is therefore a diilicult problem for refineries to obtain asufficient amount of an inexpensive solvent distillate to reduce theviscosity of the large amounts of the viscous residuums ob tained indistillation operations to obtain a marketable product, since gas oilstocks or other high boiling distillates usually employed have becomemore valuable as a cracking stock for the production of syntheticgasoline.

In distilling a lubricating distillate or a gas oil fraction at normalatmospheric pressure, from crude petroleum or petroleum residues, theoil is heated in tubular stills or shell type stills to hightemperatures to remove the high boiling distillates desired.

In operating a tubular still for this purpose, temperatures as high as700 to 800 degrees F. or somewhat higher may be employed and even ashigh as 850 degrees F. may be employed ii a large yield of distillate isrequired. This high temperature is necessary to supply the heat ofvaporization to permit the desired fractions to distill when the oil isdischarged into the evaporator, the temperature being so regulated inthe heating step that suflicient heat is provided in the body of oil tofurnish the heat of vaporization, with the result that the residues arevery materially cooled from the temperature at which the oil entered theevaporator. This cooling effect may be as much as 50 degrees more orless, depending upon the amount distilled ofi in the form of adistillate. The residue derived from this operation, it cooled downimmediately by heat exchangers or coolers, would be found to be of aviscous nature and usually unsuitable for fuel purposes, due to its highviscosity. This is especially so where a large percentage of distillatehas been taken 01f. The residue may even 50 partake of the nature of anasphalt where a. naphthenic base oil has beenprocessed; or a heavy waxyresidue when a paramn base oil has been used, the latter also having ahigh cold test which makes it further unsuitable for fuel oflrequirements.

It is well known in the art that heavy or viscous petroleum oils may beheated in a cracking apparatus to a temperature suflicient to crack thehydrocarbons, then distilling oil the lighter fractions and leaving aresidue whose viscosity is lower than the original oil. The sedimenthowever, is high where cracking is resorted to and often makes the oilunsuited for sale without admixture of other low sediment oil to averagedown the sediment and free carbon.

Now I have discovered that it the lubricating distillate or gas oilfraction is distilled in the evaporator from the original charging stockand the residue still retaining its heat after evaporation is permittedto accumulate in the bottom of the evaporator, the viscosity of theresidue will be materially reduced but will have a high sediment andfree carbon content which render it unsuitable for sale. This is truewhen the evap- .85 orator is working under substantially atmosphericpressure.

I have also discovered that if a superatmos pheric pressure ismaintained on the evaporator the sediment and free carbon is greatlyreduced but this again has a serious drawback in the fact that if a highpressure is maintained on the evaporator suflicient to prevent carbonformation in the residue, then more heat has to be applied to thecharging stock and its temperature raised in order to evaporate thedesired lubricating distillates or gas oil fractions because thepressure raises their boiling point. Now this increased temperature inturn tends to increase the carbonization of the oil, principally theheavy residue, with the result that more sediment .and free carbon areproduced, rendering the residue unsalable or at least lessening itsvalue.

However, it may be found desirable to carry a certain amount of pressureon the evaporator to permit carrying a higher temperature on .theingoing oil and at the same time to obtain the desired yield ofdistillates in order to furnish suflicient heat to the residue for itssubsequent decomposition, but this pressure is only nominal the pressureemployed on the evaporator and at such a temperature that the residuewill have suiiicient heat to bring about the desired decomposition ormolecular rearrangement in the subsequent digestion and pressure stepand.

wherein the residuals immediately removed from the evaporator by a pumpand discharged into a pressure digester or reservoir preferablyinsulated, so the oil will not lose its heat; and the digester reservoiris made with a capacity such that it will hold the oil in transitthrough it for a suitable length of time so that a conversion of thehydrocarbons will take place and a residue will result which has muchgreater fluidity than the original oil entering the reservoir.Furthermore, the process employs a comparatively high pressure on thedigester or reservoir to prevent any considerable evaporation of thelower bofling fractions generated by the decomposition of the highboiling vlscous hydrocarbons, which comprise the original residueentering the digester or reservoir, and I have discovered that inpreventing this evaporation by impressing a pressure upon the oil in thedigester or reservoir by the charging pump of such a magnitude that itwill exceed the vapor pressure of the lower boiling fractions generatedby the decomposition above referred to, the sediment and free carbonresidue will be negligible and will meet fuel oil specifications withoutadmixture with other low sediment fuel or' lighter distillates to makeit salable.

The pump pressure and the pressure on the digester or reservoir may beas high as 500 lbs. per sq. in. or more, depending upon the oil treated,some oils requiring as high as 700 lbs. or more and in some cases apressure'less than 500 lbs. may be suflicient.

The time in which the oil is retained in the pressure reservoir alsodepends upon the character of the oil and maybe aslong as an hour ormore. In some instances a shorter time may sufllce to bring about thedesired decomposition of the viscous residue. I have also discoveredthat coincident with the increased fluidity of the resulting residuethat the cold test hasbeen lowered very materially, in some cases asmuch as 30 degrees F.

As an example of the application of my invention for obtaining a highboiling distillate or'cracking stock for the production of syntheticgasoline and a marketable residuum suitable as a fuel oil from fuel oilobtained in general reflnery practice, a naphthenic base fuel oil havinga gravity of 17.5 degrees A. P. I. and a viscosity i of approximately 85seconds at 122 degrees F.

(Saybolt Furol viscosimeter) was heated to a temperature of 780 F. undera pressure of approximately 99 pounds gauge, and then subjected to adistillation operation at a pressure of approximately 10 pounds gaugeand 40 per cent of a high boiling distillate or gas oil stock wasdistilled oil, leaving a heavy asphaltic residuum which was semi-solidat ordinary temperature and not sufficiently fluid at 122 degrees F. toobtain a Saybolt Furol viscosity determination.

This heavy asphaltic residuum coming from the distillation operation,and while retaining its heat from the distillation operation, was thensubjected to digestion at an avera e e p ature of 130 degrees F. for 60minutes and under a pressure of over 700 lbs. gauge and after cooling,the viscosity was reduced to 123 seconds at 122 degrees F. (SayboltFurol viscosimeter).

One of the objects of this invention is to provide a process wherein aresidue from a distillation process is rendered more fluid.

Another object of the invention is to produce a residue of low sedimentand substantially free from uncombined carbon content.

Another object is to produce a final residue of lower cold test than theoriginal residue.

Another object of the invention is to reduce the viscosity of viscouspetroleum residuums by a molecular rearrangement to produce a marketablefuel oil without the use of solvent petroleum oil distillates.

Another object of the invention is to utilize the retained heat of thepetroleum oil residuum coming from a distillation operation to reducethe viscosity of the petroleum oil residuum.

Another object of the invention is to obtain a maximum yield of highboiling distillates from as petroleum oil and a marketable residuumsuitable as a fuel oil.

Another object of the invention is to provide an apparatus to carry outthe process in a continuous manner.

From the foregoing description of the process it will be seen that acontinuous process is described that has many features of novelty andthe apparatus later to be described shows the equipment necessary tocarry on the process.

The drawing represents a diagrammatic view of the apparatus in which theparts are in vertical section.

In the drawing, 1 representsa tank for holding the oil to be processed,such as an asphaltic or mixed base crude petroleum oil, from which thelower boiling hydrocarbons may or may not have been separated by a priordistillation operation.

Tank 1 is fllled with the petroleum oil to be processed by opening valvein the pipe 71. From tank 1 the oil flows through pipe 4 and into thesuction side of pump 2 which discharges the same in a regulated streamflow through pipe 5, heat exchanger 3, pipe 10, heat exchanger 14, pipe18, heat exchanger 61, pipe 64 and heating coil 6'1, under a pressuresumcient to prevent any substantial vaporization. is stationed in thetop of furnace 68. The furnace 68 is provided with a burner 65 stationedin the lower section of the furnace. The burner 65 is connected to asource of fuel supply not shown and regulated so as to supply asufllcient amount of heat to heating coil 67, to heat the preheated oilpassing through the coil 67 to a temperature ranging from 700 to 800degrees F. or more, this temperature depending upon the boiling pointsof the distillates to be separated from the petroleum oil stock and theheat required in the residue to bring about the decomposition ormolecular rearrangement desired without extensive cracking and formationof low boiling hydrocarbons. In case it is desired to separate arelatively low boiling distillate only,

Heating coil 67- a lower temperature than 700 degrees F. may be apressure regulating valve 53. Pipe 66, ending in spray pipe 49,discharges the heated oil into fractionating tower 46 wherein the lowerboiling oils or naphtha stock together with a higher boiling distillateare vaporized and separated from the residual products. Thefractionatlng tower 46 is provided with boiling decks 48 in the lowersection and a separator plate 47 located just above the boiling decks48. The fractionating tower 46 is also provided with boiling decks 88situated above the separator plate 47 and a spray pipe for theintroduction of a wash oil to condense and separate the higher boilingdistillate from the vaporized lower boiling oils or naphtha stock.

The vaporized oil passes up through boiling decks 48 then through thevapor outlet in separator plate 47 and into the top section offractionating towerv 46, whereby the vaporized oil is separated from theresidual products. The vaporized oils passing up through boiling decks88 are fractionated and the higher boiling fraction condensed by thecontinuous introduction of a cooler wash oil introduced through spraypipe 45. The lower boiling vaporized naphtha fraction, (if present inthe oil being processed) separated from the higher boiling oils, passesout of fractionating tower 46 at the top through pipe 44, valve 44 andinto condenser coil 43 which is stationed in condenser box 42, whereinthe major portion of the naphtha stock is condensed and passes throughpipe 40 into look box 39. In look box 39 the condensed naphtha stock isseparated fromthe gaseous product and passes through pipe 38 intoreceiving tank 37. From tank 37 the naphtha stock may be conducted to astorage not shown through pipe 69 controlled by valve 70, and purifiedby methods known in the art. The gaseous products separated from thenaphtha stock in look box 39 pass through pipe 41 into pipe 87. Pipe 87leads to an absorber not shown whereby the retained naphtha stock isseparated from the non-condensable gaseous products and returned to tank37 or to other storage not shown.

The condensed higher boiling distillate and wash oil stock whichcollects above the separator plate 47 passes out of the fractionatingtower 46 through pipe 50 and into the suction side of pump 63, whichdischarges the same through.

pipe 62, heat exchanger 61, pipe pipe 58 and into receiving tank-57.

A portion of the cooled higher boiling distillate which collects in tank57 is continuously returned to fractionating tower46 passing from tank57 through pipe 56 into the suction side of pump 55. Pump dischargesthis distillate through pipe 54 which terminates in spray pipe 45 in thetop of fraci'ionating tower 46. The excess quantity 60, cooler 59,

' 01 high boiling distillate which collects in tank 57 is continuouslyor intermittently conducted to a storage not shown by opening valve 90in the pipe 90 and may thereafter be cracked for the production ofgasoline stock or utilized for the manufacture of other petroleum oilproducts known in the art.

The residuum or residual oil product at a temperature of approximately700 to 800 degrees F. or more collects in the bottom of i'ractionatingtower 46 and immediately and continuously passes out of tower 46 throughpipe 52 into the suction side or pump 51. Pump 51 continuouslydischarges the hot residuum through pipe 22 which ends in a spray pipe23 inside of digester 19 near the top. The digester 191s maintainedunder a pressure suflicient to prevent any substantial vaporizationtherein, which may be as high. as 700 pounds gauge or more, dependingupon the temperature of the'residuum, the time of digestion and theextent of decomposition.

By a regulated closing of valve 44, fractionating tower 46 may bemaintained under any pressure so as to regulate the percentageseparation of lower boiling oils from the higher boiling fraction andwhereby the residual oil passing to the digester 19 may be maintained attemperatures sufliciently high to obtain the required decomposition. Thepressures maintained on pipe 22 and digesier 19 are indicated bypressure gauges 20 and 21.

It will be noted that in my preferred form of apparatus that thereaction reservoir or digester 19 is a vertical cylinder with the inletfrom the charging pump 51 at the top ending in a spray pipe 23, so thatas the oil is withdrawn from the bottom outlet of the digester into pipe15 controlled by pressure regulating and discharge valve 17, there is agradual flow downward of the oil in the reservoir or digester 19, thelatter being kept full or at the height of the inlet (spray 1 pipe 23)and due to the fact that the inlet oil is hotter than the oil withdrawnfrom the bottom outlet, there is no tendency to intermix due toconvection currents and the oil remains in the reservoir or digesler 19for the required reaction time. 1

The digester 19 is preferably covered with an insulating coating such ascork, magnesia or other insulating material 19' to prevent loss of heatfrom radiation. The digester 19 is also provided 9 with the pressureregulating and discharge valve .25 connected to a liquid level controldevice as indicated on the drawing. The pressure regulating anddischarge valve 25 may be set for any pressure desired, and when thatpressure is ex- 3 ceeded will discharge the fluid content from the topof digester 19 into pipe 24. I

From pipe 24 the fluid content, which may be hot residuum or hydrocarbongases, pass into fractionating tower 26. From the digester 19 theprocessed residuum passes through pressure regulating and dischargevalve 17, pipe 15, heat exchanger 14, pipe 16 and then intofractionating tower 26. Fractionating tower 26 is provided with boilingdecks 27 and evaporating trays 28. In fractionating tower 26 the naphthastock and gaseous products produced inthe digesting operation of theresiduum together with the naphtha stock and gaseous products comingthrough pipe 24, are separated from the processed residuum. Theseparated naphtha stock and gaseous products pass out of fractionatingtower 26 through pipe 30, cooling coil 31, which is stationed in coolingbox 36, pipe 32 and into look box 33 wherein the non-condensable gasesseparate from i the nahptha stock and pass out of the look box 33 at thetop into pipe 85. From pipe the gaseous products pass into pipe 86 whichis connected to an absorber not shown wherein the retained naphtha stockmay be recovered. From 1 look box 33 the condensed naphthastock passesthrough pipe 34 and is collected in tank 35. By means of pipe 83controlled by valve 84, the collected naphtha stock maybe conducted to.a storagenot shown. a

From fractionating tower 26 theprocessed residuum continuously passesinto pipe 13 and then into the suction side of pump 12, the flow beingcontrolled by operation of valve 29. The pump 12 discharges the hotprocessed residuum l through pipe 11, heat exchanger 3, pipe 6, cooler'I, pipe 8 and then into tank 9. The hot processed residuum passingthrough heat exchanger 3 and cooler 7 is cooled tothe required degree.From gtankiitheprocessedresiduummaybetransported to other storage notshown through Pipe 81 controlled by valve 82 and may thereafter beutilized as a fuel oil or other marketable residual oil product known inthe art.-

By the clause suflicient to prevent substantial vaporization", as usedin the specification and claims of this application, it is meant thatapproximately 10 per cent or less of the residual 011 being processed isin a vapor form, and insumcient to cause carbonization.

While the process herein described is well adapted for carrying out theobjects of the invention, it is to be understood that variousmodincations and changes may be made without departing from the spiritof the invention, and the invention includes all such modifications andchanges as come within the scope of the appended claims.

What I claim is: Y

i. A method of processing petroleum oils, comprising, separatelyseparating by low pressure distillation and fractionation a lowerboiling distillate, a. higher boiling distillate, and a viscouspetroleum oil residuum from a petroleum oil, at temperaturessubstantially not less than 100 F., continuously passing the heatedpetroleum residuum without further heating, and at a temperature of itsretained heat from the low pressure distillation operation, through anenlarged digesting zone maintained at an increased pressure of about 500pounds per square inch, sufiicient to prevent substantial vaporizationtherein, and at a temperature of not less than about 700 1 N8- iatingthe time of flow through the digesting zone suiiicient to produce amolecular rearrangement of the heated petroleum residuum, and producinga fuel oil of lowered viscosity.

2. A method of processing petroleum oils, comprising, separatelyseparating by low pressure distillation and fractionation adistillateand a viscous petroleum oil residuum from a primary residual petroleumoil, at temperatures substantially not less than 100 l"., continuouslypassing the heated viscous petroleum oil residuum, withoutfurtherheatingandatatemperatureofitsre tained heat from the low pressuredistillation operation, through an enlarged digesting nonemaintainedatanmcreasedpressureofaboutmpoundspersquareineh,suilloienttopreventmbstantial vaporization therein,and at a temperature of not less than about 100 R, regulating the timeof flow ofthe heated viscous petroleum 'oll residuum through thedigesting none suihclent to produce a molecular rearrangement of thehated viscous petroleum residuum, and producing a fuel oil of loweredviscosity.

3.1hatstepinthenyethodofprocessingviscous petroleum oil residuum torender the same less viscous, comprising, passing a heated viscouspetroleum oil residuum, from which distiliatesdigestingsoneforaboutsixtymlnuteetoprroduee 1,ess,eos

have been separated by distillation and fractionation of a petroleumoil, without further heating and at the temperature of its retained heatfrom the distillation operation, through anenlarged digesting zonemaintained at an increased pressure of about 500 pounds per square inch,suiiicient to prevent substantial vaporization therein, and at atemperature of not less than about 700 F., regulating the time of flowthrough the digesting zone sufilcient to produce a molecularrearrangement of the heated viscous petroleum oil residuum, andproducing a fuel oil of lowered viscosity.

4. A method of reducing the viscosity of vis-' cous petroleum oilresiduum, comprising, subjecting heated viscous petroleum oil residuumcoming from a low pressure distillation and fractionation operation, ata temperature of not less than about 700 F., to an increased pressure ofabout 500 pounds per square inch, produced by mechanieal means,sufllcient to substantially prevent further vaporization thereof, andthen without further heating passing the heated residuum at saidpressure and said temperature through an enlarged digesting zone,regulating the time of 0 flow of the heated residuum through thedigesting zone to produce a molecular rearrangement of the heatedresiduum, and producing a fuel oil of lowered viscosity.

5. A method of reducing the viscosity of vis- 106 cous petroleum oilresiduinn, comprising, subjecting heated viscous petroleum oil residuum,coming from a distillation and fractionation operation, at a temperatureof not less than about 700 R, to a pump pressure of about 500 pounds 11'per square inch, sumcient to prevent substantial vaporization thereof,and without further heating passing the heated residuum at said pressureand said temperature through an enlarged digesting zone, regulating thetime of {low of the heated residuum through the digesting zone toproduce a molecular rearrangement of the heated residuum, and producinga fuel oil of lowered viscosity.

8. A method of processing petroleum oils, canprising, separatelyseparating by low pressure distillation and fractionation a lowerboiling distillate. a higher boilingdistillate, and a viscous petroleumoil residuum from a petroleum oil. at temperatures substantially notless than 700' 1' continuously passing the heated petroleum residuumwithout fin-ther heating, and at a temperature of its retained heat fromthe low pressure distillation operation, through an enlargeddigestingzonemaintainedatanincreasedpressure of about 500 pounds'persquare inch-sulcient to prevent substantial vaporization therein, and ata temperature of not less than about 700' ll, regulating the time offlow through the amolecularrearrangementoftheheatedpetroleum residuum.and producing. a fuel oil (I lowered viscosity.

JOHN C. BLACK. u

